关键词: 土地, 土地利用, 土地覆被, 土地利用/覆被变化

Abstract: Land use/cover change has become one of the most active fields in the current inter-national study on global changes,and many results have been obtained in recent years especially in relevant theories and methodologies in this field.However,quite many problems in the study of land use/cover change have to be more deeply explored because of its complexity.In this paper the following issues in the study of land use/cover change are explored. 1.Classification of land use/cover changes.More attention should be paid to the classifica-tion of land use/cover changes from the point of view of dynamic process.According to this idea,both land use change and land cover change could be divided into three types,i.e.,'conversion','modification' and 'maintenance'.Among them 'modification' has received more attention from researchers in this field at present. 2.Driving force of land use/cover changes.The driving force of land use/cover changes should be divided into two categories,i.e.,the biophysical driving forces and the socio-economic ones.In most cases,the former will cause changes of land cover instead of land use.On the contrary,the latter usually has direct impacts on the changes of land use through human's decision on land use.In addition,due to its increasingly notable and profound roles of human socio-economic activities in land use/cover changes,the socio-economic driving force of land use/cover changes could be further divided into 'general driving force'(indirect driving force) and 'direct driving force'. 3.Modeling of land use/cover changes.Different kinds of models used in the study of land use/cover changes have been worked out in recent years.However,these models all have their own advantages and limitations.Besides,those models which are capable to simulate dynamically the competition between different types of land use are nearly absent and,therefore,should be created.In addition,any model worked out and can be used in simulating the land use/cover changes must have a reliability in terms of theoretical background. 4.The issue of scale in the study of land use/cover changes.Scale,including spatial scale and temporal one,is a significant concept in the study of land use/cover changes.In classification of land use/cover change and in the studies on driving forces of land use/cover change and analysis on their impacts the scale sense have to be always kept in mind.In addition,the optimum spatial and temporal scales should be selected and determined in the study of land use/cover changes.

Key words: land, land use, land cover, land use/cover change